Fisheries declines, a global concern

A commercial fishing boat. Photo credit: Wiki Commons.

Many culturally and commercially-important fish species, including tuna and mackerel, are experiencing dramatic population declines, some by as much as 75%. However, the extent of such declines is not fully understood, as this is limited by the availability of biological survey data. Although the majority of marine fisheries studies rely on quantitative data to give concise estimates of population declines, unconventional data sources are increasingly used to estimate baselines of data-poor fish species. Unconventional data sources include traditional and local ecological knowledge (TEK and LEK, respectively). LEK refers to a lifetime of accumulated ecological observations, while TEK is composed of similar observations, passed inter-generationally, and woven into the fabric of Indigenous peoples’ culture, practices, and beliefs.

Integrating past with present

TEK and LEK are recognized for their ability to complement ecological data and improve fisheries management. Because of their geographical, cultural, and subsistence ties to marine resources and coastal ecosystems, Indigenous and local communities possess valuable knowledge about species that are scientifically data-poor. Many of these people have been fishing their entire lives, and their accounts of “good and bad” years for certain fish species represent a crucial perspective for assessing long-term changes in fisheries. You may have experienced TEK or LEK if you’ve talked to fishermen or people whose lives are closely tied to coastal ecosystems; these people may share invaluable insight about changes in the landscape that scientific surveys may overlook.

Why is this important?

Due to the interwoven aspect of culture, tradition, and fisheries, TEK and LEK from fishers and Indigenous knowledge holders can expand current understanding of changes in species and inform fisheries conservation goals.

The study

Archaeological evidence indicates that First Nations of coastal British Columbia (BC), Canada, have harvested Yelloweye Rockfish, an important cultural and economic resource, consistently for at least 1800 years. This fish species is very long-lived (up to 118 years!!), and adults of the species inhabit deep waters and rocky outcrops. Recently, First Nations of BC’s Central Coast have observed declines of Yelloweye Rockfish and other rockfish, which they attribute primarily to over-exploitation by commercial and recreational fishers.

Yelloweye rockfish, Sebastes ruberrimus. Photo credit: Wiki Commons.

While Yelloweye rockfish are important resources of the First Nations, this species is also targeted by commercial fishers. They are also vulnerable to overfishing because of their slow life history traits and their susceptibility to barotrauma when they are brought to the surface by fishers. As part of their slow growth, their reproductive potential increases with size and age; since fishers tend to target larger individuals, Yelloweye Rockfish likely suffer reduced population productivity. Because of these factors, this fish is listed as a species of special concern in Canada.

Map of the study area, the coast of British Columbia. Photo credit: Wiki Commons.

The authors’ goal was to use the Central Coast of BC as a case study to illustrate the use of TEK and LEK to establish historical baselines that extend farther back in time than modern scientific surveys. To do this, the authors interviewed Indigenous fishers of the First Nations of British Columbia. Interviewees were asked about changes in yelloweye rockfish catch size, abundance, body length, and perceived causes of changes to rockfish populations. Most participants provided information about their earliest and most recent years of fishing experience, which aided the authors’ analysis of changes in rockfish over time. Responses of the participants were compared with current biological survey data to determine if these two distinct data sources presented similar trends in yelloweye rockfish populations.

Results

Of the 42 First Nations community members that participated in the interviews, most observed a decrease in individual yelloweye rockfish length since the 1980s. Nearly 98% of respondents also reported that they noticed a substantial decrease in abundance of yelloweye and other rockfishes since the 1950s.

As the authors expected, the information provided by Indigenous fishers aligned with scientific surveys that have reported declining yelloweye rockfish body sizes. This illustrates just how valuable it can be to take into account local knowledge when assessing changes in species over decadal timescales.

Participants were asked what they thought were the major stressors responsible for observed decline in yelloweye rockfish populations. Nearly 50% of respondents said that commercial trawling was a major driver in yelloweye rockfish abundance declines. Others reported the longline fishery, sports fishing, forestry impacts, earthquakes, and climate change as important factors.

About 90% of participants told the authors that they had noticed the impacts of climate change over their lifetimes, mainly in the form of less snowpack during milder winters, and hotter and drier summers. Though it is difficult to attribute declines in rockfish abundance strictly to changing climate, respondents acknowledged that changing water temperatures could have impacts on rockfish in the foreseeable future. Speaking of the future, nearly one-third of respondents expressed concerns about fisheries stock depletions, which would lead to loss of cultural traditions, diet, and language.

The bigger picture

This study illustrates how TEK and LEK can be gathered and used to establish historical baseline estimates that reach back further in time than scientific surveys. We live in a time in which our oceans are increasingly threatened by a growing number of stressors, it is important to call back to the past, to integrate local societal observations of changes in marine resources with ongoing research.

A snapshot of the coast of British Columbia, highlighting the development of coastlines. Featured image. Photo credit: Wiki Commons

An important implication from this study is that the future of yelloweye rockfish may be compromised if larger individuals that have higher reproductive potential continue to be collected by commercial fishers.

The methods used in this study can be applied to other fisheries around the world. In addition, by interviewing Indigenous community members, the authors provided an opportunity for increased community engagement and potential for fisheries management to uphold Indigenous rights.

Hopefully, this study will inspire other local and tradition-based knowledge to be incorporated into the framework of scientific marine surveys and conservation planning.

Kate is a 2nd year PhD student in the Biological Sciences Department at the University of Notre Dame, and holds a Masters in Environmental Science & Biology from SUNY Brockport. She studies benthic-pelagic ecosystem linkages in the Great Salt Lake, Utah. Outside of lab and field work, she enjoys running and kickboxing.

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Discussion

One Response to “Beyond word of mouth: How local knowledge can fill fisheries data gaps”

Great points. If there was a easy to use, and also available for these costal communities website to accumulate data like this im sure we could cover much of those grey areas. In Fiji I always speak with the local fishermen from all across Oceana and their responses always vary, but they do not record the information at a data base. Im sure such initiatives could be created with a push or two from local community administrations if not government intensives among the fisheries.